1. Field of the Invention
The present invention relates to a semiconductor package, and more particularly, to a semiconductor package capable of effectively radiating heat produced in the interior thereof.
2. Description of the Related Art
As semiconductor packages having semiconductor chips mounted therein are highly integrated and operated at high speeds, their operation speeds have been greatly increased and their sizes have been reduced. This leads to higher temperatures in the packages, especially for multi chip packages (MCPs), which contain two or more chips in one package. High temperatures in the interior of a package can cause stress on the chips mounted in the package and often result in malfunctions. The operation speed of the chips is also reduced by high temperatures. Particularly, the refresh characteristics of DRAM semiconductor chip are degraded with high temperatures in the packages.
FIG. 1 shows the heat spreading path in a typical semiconductor package. The semiconductor package is illustrated as an example of a 1-chip 1-package having one semiconductor chip.
As shown in this figure, the typical semiconductor package 10 includes a semiconductor chip 11, a printed circuit board (PCB) 12, at least one solder ball 14 electrically connecting the semiconductor chip 11 to the PCB 12, and at least one solder ball 15 electrically connecting the semiconductor package 10 to the outside. The semiconductor package 10 is connected to a circuit board through the solder ball 15 to receive power and signals, which are required in the semiconductor chip 11, from the outside.
The arrows in this figure indicate heat spreading paths. The solid arrows indicate the paths along which heat spreads through air, and the dotted arrows indicate the paths along which heat is conducted through materials inside the semiconductor package to the outside.
As shown in this figure, heat is spread to the outside through both the air and the material inside the semiconductor package. Although heat produced in a semiconductor package is generally conducted through a board and effectively spread to the outside, only a small amount of heat is spread through the top of the package.
A conventional method of helping spread heat more efficiently is to attach a heat sink to the top surface of the semiconductor package in order to reduce the temperature inside the semiconductor package. FIG. 2 is a sectional view of a semiconductor package with a heat sink attached to the top surface of the semiconductor package.
As shown in FIG. 2, the semiconductor package 20 may include one or more semiconductor chips 22 and 23, substrates 24 and 25 each having a semiconductor chip stacked thereon, and one or more solder balls 27. A molding member 26 may be formed on the semiconductor package 20 to protect the semiconductor chips stacked inside the package. A heat sink 21 may be further attached to the top of the package to radiate heat produced in the package.
However, multi-chip semiconductor packages such as dual stack packages (DSPs) or quad stack packages (QSPs) produce a great amount of heat, but there is a limit to the amount of heat that can be radiated. Further, there is a problem in that internal chips of a multi-chip package may reach different temperatures, which may affect the reliability of the internal chips and the package as a whole.